Lập trình mạng P7

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To send JavaMail, you'll need to add at least two JAR files from Sun to your classpath (placing them in a lib directory may be a good idea) activation.jar mail.jar (Note: You can download these files from the Java Zone) For more complex emailing tasks (like receiving or managing pop3 or imap mail servers), you'll need to download additional files like pop3.jar and imap.jar. You will also need access to a mail server and possibly a username/password

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Java Training Introduction to Java Mail
What is JavaMail? -1 JavaMail is an API for sending and receiving email using Java. The current version is 1.3.1 and can be downloaded from Sun's website at: http://java.sun.com/products/javamail/ Possible uses: Send email from web pages using servlets Create a GUI email client Send email from Java stored procedures Send email from any type of Java application Spam your friends and enemies! (read email addresses from a database, write a for () loop, and away the emails go!)
What is JavaMail? -2 To send JavaMail, you'll need to add at least two JAR files from Sun to your classpath (placing them in a lib directory may be a good idea) activation.jar mail.jar (Note: You can download these files from the Java Zone) For more complex emailing tasks (like receiving or managing pop3 or imap mail servers), you'll need to download additional files like pop3.jar and imap.jar. You will also need access to a mail server and possibly a username/password for that mail server
How Does Email Work? In general, each internet domain has an email server. When you send out an email Your email client program sends the message to your email server Your email server contacts the addressee's email server using the SMTP (simple mail transfer protocol) Your email server verifies that the addressee's user name is valid Your email server then transfers the email to the addressee's email server When the addressee logs into his email server (using his email client program), he gets his email
Mail Servers (sendmail)-1 sendmail is the most commonly used mail server in the world, as it generally comes free with Unix and Linux installations very powerful and flexible. Supports POP3 and IMAP well documented (lots of books on setting up sendmail) long track record (first version appeared in early '80s) tedious to set up (lots of cryptic configuration files) free www.sendmail.org
Mail Servers (qmail)-2 qmail is probably the most popular alternative to sendmail in the UNIX world perhaps more secure than sendmail (at least older versions of sendmail) Easier to set up and administer than sendmail pretty good documentation (several books written on qmail in the past few years) free http://www.qmail.org/top.html
Mail Servers (MS Exchange)-2 MS Exchange is widely used in the Windows world, especially in corporate environments that use MS Office (and hence MS Outlook) Expensive Integrated into MS Active Directory GUI administration tools are easier to learn for Windows people MS Outlook is a powerful and slick email program that will work with Exchange, sendmail, or qmail. It does, however, have a history of security vulnerabilities and some organizations refuse to use it because of that.
POP3, IMAP, MAPI -1 Currently, the most popular protocols are POP3 (Post Office Protocol, version 3) IMAP (Internet Message Access Protocol) MAPI (Messaging Application Programming Interface-- Microsoft Windows email interface)
POP3 POP3 is the oldest and most widely used. It was designed to support offline mail processing. Mail is delivered to a server and a user's computer runs a mail client program to download any new mail Once messages are delivered, they are generally deleted from the mail server This minimizes disk space requirements for mail server, but ties the mail to a particular machine. If user goes to another computer, he can't access his mail POP3 has limited support for reading mail online (and leaving the mail on the mail server) Simpler protocol than IMAP makes it easier to implement. More POP3 mail clients available
IMAP IMAP Developed at University of Washington Primarily used to access mail and leave it on the mail server. This allows users to access their mail from any computer Requires more disk space to store email messages Can work in "offline" mode like POP3 Easy to manage multiple mailboxes Supports tagging emails with flags like "read", "deleted", "answered", etc.
MAPI MAPI Set of C functions (API) developed by Microsoft and supported in MS Exchange/Outlook Also supported by Eudora Mail For more info, type the following search string in Google: "MAPI site:msdn.microsoft.com"
Apache James Mail Server Apache has a free mail server called James Supports POP3, SMTP, and NNTP Download the binary file .ZIP version (for Windows) .TAR version (for Linux) Uncompress it and then run “run.bat” (Windows) or “run.sh” (Linux) to start the mail server Download from here: http://james.apache.org/download.cgi
NOAA Mail Server You can use ESRL/NOAA’s email server email.boulder.noaa.gov mailProperties.setProperty("mail.smtp.host","email.boulder.noaa.gov"); This will work IF you send emails to @noaa.gov email addresses (like jeff.s.smith@noaa.gov) When I tried to send an email to jeffssmith1@yahoo.com I got this error message Invalid Address Relaying not allowed: jeffssmith1@yahoo.com
Using JavaMail -1 Once you have a mail server you can use (either James or another mail server), you can send emails through it by using JavaMail In general, to send a plain text email using JavaMail, you do the following: Get a mail session instance Create a MimeMessage object (passing in the mail session instance into the constructor) Set the MimeMessage object's properties (like the toAddress, fromAddress, message, etc.) Send the message
Getting a Mail Session Get a mail session for the James mail server. If James is running on your own computer, your mail.smtp.host is localhost. If your mail server is a remote computer, it might be something like “mailgate.fsl.noaa.gov” Get a mail session for the James mail server private Session getMailSession() throws Exception { Properties mailProperties = new Properties(); mailProperties.setProperty("mail.transport.protocol", "smtp"); mailProperties.setProperty("mail.smtp.host", "localhost"); return Session.getInstance(mailProperties, null); }
Plain Text Email Example Next, send your email using the mail session MimeMessage msg = new MimeMessage(getMailSession()); msg.setFrom(new InternetAddress("bill.gates@msn.com")); msg.addRecipient(Message.RecipientType.TO, new InternetAddress("larry.ellison@oracle.com")); msg.setSubject("RE: Oracle vs SQL Server"); msg.setText("SQL Server is better than Oracle"); Transport.send(msg);
Exceptions and imports Your code which sends an email will need to catch the following checked exceptions: Exception MessagingException AddressException You should import the following packages: import javax.mail.*; import javax.mail.internet.*;
HTML Email You can also send HTML email with JavaMail. HTML email can be used to Use different size fonts imbed images into your email Use different colored text, bold, italic, etc.
HTML Email With HTML email, you set the mime message content type to "text/html" call the setContent() method to set your html content It helps to know a little HTML!
Mail Security Virtually all mail servers require a username and password to receive email Some mail servers require a username and password to send an email (by default, James does not). This prevents spammers from hijacking the mail server to send unauthorized email JavaMail supports this username/password authorization and authentication To implement this, you get a transport object from the mail session and call the connect() method with the mail host, username, and password See next slide for code example